import?java.io.IOException;
import?java.net.DatagramPacket;
import?java.net.DatagramSocket;
import?java.net.InetAddress;
import?java.net.SocketException;
import?java.net.UnknownHostException;


public?class?UDPCilent?{

	public?static?void?main(String[]?args)?{
		try?{
			/*
			?*?向服務器端發送信息
			?*/
			//定義服務器ip，端口，信息
			InetAddress?address=InetAddress.getByName("localhost");
			int?port=8000;
			byte?[]data="用戶名：kuerban;密碼：668858".getBytes();
			//建立DatagramPacket
			DatagramPacket?packet=new?DatagramPacket(data,?0,?data.length,?address,?port);
			//建立DatagramSocket
			DatagramSocket?socket=new?DatagramSocket();
			socket.send(packet);
			
			/*
			?*?獲取服務端發送信息
			?*/
			//建立數據包接受信息
			byte?bytes[]=new?byte[1024];
			DatagramPacket?packet1=new?DatagramPacket(bytes,?bytes.length);
			socket.receive(packet1);
			String?info=new?String(bytes,?0,?packet1.getLength());
			System.out.println(info);
			socket.close();
		}?catch?(UnknownHostException?|?SocketException?e)?{
			e.printStackTrace();
		}?catch?(IOException?e)?{			
			e.printStackTrace();
		}
	}
	

}


import?java.io.IOException;
import?java.net.DatagramPacket;
import?java.net.DatagramSocket;
import?java.net.InetAddress;

/*
?*?服務器端，基于UDP實現用戶登錄
?*/



public?class?UDPServer?{

	public?static?void?main(String[]?args)?{
		try?{
		/*
		?*?接受信息
		?*/
			
			//建立一個DatagramSocket,指定端口
			DatagramSocket?socket=new?DatagramSocket(8000);
			byte?[]bytes=new?byte[1024];
			//建立一個Datagrampacket，以接受數據
			DatagramPacket?packet=new?DatagramPacket(bytes,?bytes.length);
		/*
		?*?發送數據
		?*/		
			//啟動服務器
			System.out.println("服務器已啟動");
			while(true){
			????socket.receive(packet);
			????//建立客戶端ip，端口
				InetAddress?address=packet.getAddress();
				int?port=packet.getPort();
				UDPthread?thread=new?UDPthread(socket,packet,address,port,bytes);
				thread.start();
			}
			
		}?catch?(IOException?e)?{
			e.printStackTrace();
		}
	}

}

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

public class UDPthread extends Thread{

DatagramPacket packet=null;

InetAddress address=null;

byte bytes[];

int port=0;

DatagramSocket socket=null;

public UDPthread(DatagramSocket socket,DatagramPacket packet,InetAddress address,int port,byte[] bytes) {

this.packet =packet;

this.address=address;

this.port=port;

this.socket=socket;

this.bytes=bytes;

}

public void run(){

//讀取信息,輸出信息

String info=new String(bytes, 0, packet.getLength());

System.out.println(info);

//建立信息，并發送

byte bytes1[]="登陸成功".getBytes();

DatagramPacket packet1=new DatagramPacket(bytes1, 0, bytes1.length,address,port);

//向客戶端響應

try {

socket.send(packet1);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}